CyberHand ● Robotic Hand for CyberBrick

CYBERHAND 🤖✋ Five fingers. Four servo channels. One printed differential to reconcile them. The CyberBrick receiver gives you four servo channels. A hand has five fingers. CyberHand closes that gap with a printed differential rocker shared by the ring and the pinky: when one finger touches the object first, the rocker keeps feeding travel to the other until both are loaded with the same force. The grip self-equalises on shapes it has never seen — exactly like your own ring and little fingers, which share a tendon path and never move fully independently. Thumb, index and middle each keep their own channel. Works with any CyberBrick transmitter, and pairs natively with the CyberGauntlet — close your fist and the printed hand closes with you, very satisfying! HOW IT WORKS ⚙️ Tendons, not gears. Four 9 g servos wind 0.6 mm nylon cord on printed R11 winch horns; the pull runs through the finger channels like a flexor tendon. It is quiet, it is compliant, and when a finger is blocked the clutch slips instead of a gear train stripping. TPU flexure knuckles — zero pins, zero bearings. Every joint is a printed TPU hinge that also acts as the return spring. No axles, no fasteners, nothing to fall out of a finger mid-build. The joint is the part. Thermoformed palm mesh. The palm shell prints flat, then a few seconds of heat let you curve it into a real anatomical shape over your hand — the technique Steve Wood pioneered on the Flexy-Hand 2. Servo bay in the chassis. The four servos, their leads and the CyberBrick receiver all live inside the palm and wrist bracket. No dangling electronics, no external servo brackets. Built on the CyberBrick kit. The Hardware Kit covers the receiver, the wiring and most of the hardware. You add 7× M3 self-tapping screws and three extra 9 g angular servos to reach the four channels. Ready-made controller config. The listing includes CYBERGAUNTLET-CYBERHAND.json — import it in the CyberBrick app, flash both boards, and all four channels are already mapped. No manual channel setup. Display stand included. Rod + base, so the hand stands on your desk instead of lying on it. ACKNOWLEDGEMENTS 🙏 The finger architecture, the TPU flexure hinge principle and the thermoform palm technique come from the outstanding Flexy-Hand 2 by Steve Wood (Gyrobot) — an open-source prosthetic hand built for the e-NABLE community. CyberHand is a heavy mechanical redesign on that foundation: new palm chassis with an internal servo bay, winch-horn tendon drive, CyberBrick receiver mount, wrist bracket, differential connector and reworked fingertips. If you like this model, go look at the original first. It was built to give people hands. 👉 https://www.thingiverse.com/thing:380665 BILL OF MATERIALS 🔩 Printed — everything is already sliced and plated in the included Bambu Studio project, TPU parts included. Nothing to source or slice separately. Hardware CyberBrick Hardware Kit (receiver + 1× 9 g servo + wiring) 3× additional angular servos — 4 servos total 7× M3 self-tapping screws (3× M3×10 of them hold the servo fixer) 0.6 mm black nylon cord for the tendons (the tendon-end screws come in the servo accessory bags) A heat gun for thermoforming the palm mesh Files — CYBERGAUNTLET-CYBERHAND.json, the CyberBrick app config with all four channels pre-mapped. Tools — flush cutters, needle-nose pliers, tweezers, small Phillips driver, heat gun. ASSEMBLY 🛠️ 15 min, one chapter per step, and deliberately slow on the fiddly parts. A printable PDF guide is attached to this listing. Print the parts and gather the hardware first, then follow along: Upload the CyberBrick firmware — import the included CYBERGAUNTLET-CYBERHAND.json, connect & flash both boards (1:19) Connect the servos — any receiver port order works at this point (1:35) Assemble all the TPU joints — start by sorting the finger bones (1:38) Assemble each finger — same technique, five times (3:00) Get your controller & connect power to both — the CyberGauntlet, or any four-joystick transmitter for testing (3:41) Install the servos in the palm chassis as shown (4:14) Mount the wrist bracket and the receiver (6:03) Mount the servo fixer — 3× M3×10 self-tapping (6:41) Cut the nylon threads to length — measured against the model (6:59) String and tension the tendons — anchor each thread with a screw from the servo accessory bag, then cap the fingertips (7:12) Testing time! — close your fist, the hand closes with you (11:30) Thermoform the palm mesh (12:42) Then the final assembly — palm mesh on, battery cover closed — and the hand goes on its stand (14:25). THE FIVE THINGS THAT DECIDE WHETHER IT WORKS 💡 Centre the servos before mounting the horns. A horn fitted off-centre costs that finger half its travel, and the only fix is pulling the servo back out. Check the hinge direction. The TPU knuckles are asymmetric. Mounted backwards, the finger fights you instead of returning on its own. Tendon tension is the build. Too loose and the servo spends its travel taking up slack, so the finger lags behind; too tight and the finger sits pre-curled at rest and never fully closes. Tune it one finger at a time. Balance the differential last, and as a pair. With the servo centred, the rocker should sit level. If it starts tilted, one finger hits its limit before the other and you lose the self-equalising grip. Heat the mesh, don't cook it. Sweep the heat gun in short passes from a distance until the sheet goes rubbery, then press it between the two mold halves. Held too close, PLA blisters and goes glossy before the whole sheet is pliable.